8.2.1.2
Description Info Screen
16
After restarting the device or during bake-out of the sensor an "Information Screen" is
displayed in the upper right-hand corner of the display with the following background.
Dew points in the range of -60 to -20°C at room temperature correspond to relative
humidity values of 0.08 to 5.37% RH. To ensure accurate measurement at the lowest
humidity values, the slightest drift effect of the humidity sensor element must be
compensated for.
Moreover, in order to guarantee the long-term stability of the dew-point sensor the
sensor element is periodically baked out. The sensor is heated every 13 h for
approximately 5 minutes and then allowed to cool down to ambient temperature.
During heating "HHOLD" appears on the display, and "CHOLD" is indicated during
cooling. The operation is indicated on the display:
H HOLD
C HOLD
The „Info Screen“ displays the current auto-calibration status:
H
HOLD
:
H
eat (The sensor element is being heated)
HOLD
(The measured value is being saved)
C
HOLD
:
C
old (The sensor is cooling down)
HOLD
(The measured value is being saved)
Bake-out is performed every time the device is connected to the mains supply, then
every 13 h. During the entire cycle, the last measured values are retained and are
qualitatively available at the outputs. No further measurements are made during the
heating phase. Therefore no alarm signal will be emitted during this period of time in
the event that a maximum permissible value is exceeded. Only after the heating/
cooling cycle has finished will the device resume measurement and alarm evaluation.
Summary of Contents for TPK 21
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